The invention relates to a tool and method for injecting treatment fluids, such as a sand consolidation agent or production stimulation chemical and an overflush fluid, into a formation surrounding an underground borehole.
It is known from U.S. Pat. No. 3,765,484 to treat an unconsolidated e.g. sandy subsurface earth formation surrounding an underground borehole by introducing a treatment fluid which comprises a consolidation agent into the pore spaces of the formation in the vicinity of the wellbore.
The tool known from this prior art reference is designed to inject a treatment fluid into the formation via perforations in a well casing. Other tools for injecting a treatment fluid into a formation via perforations in a well casing are disclosed in U.S. Pat. Nos. 3,487,877; 3,593,910 and 3,861,465.
The known tools generally comprise a pair of axially spaced packers which define an annular space via which the treatment fluid is injected into the surrounding perforations.
A limitation of the known tools is that they are designed to inject a batch of treatment fluid over a limited length interval via perforations into the formation. If parts of the formation surrounding perforations at different levels in a well are to be treated then the tool is moved to another level and the injection of a batch of treatment fluid is repeated once the tool has been positioned adjacent the perforations.
It is an object of the present invention to provide a tool and method which are able to inject treatments fluids, such as a sand consolidation agent, stimulation chemicals and/or overflush fluids over a long interval into a formation surrounding an underground borehole.